1. Field of the Invention
The invention relates to a testing apparatus having a function for supplying image data to an image forming apparatus and, more particularly, to a verifying apparatus for verifying a printer controller.
2. Related Background Art
As shown in FIG. 27, a printer as an image output apparatus is connected to a host computer having a printer driver via a network, USB, an interface, or the like. The printer comprises: a controller unit for converting intermediate output data formed by an apparatus such as a host computer or the like from printing source data into output image data suitable to be outputted; and an engine unit for obtaining the output image data outputted from the controller unit and outputting an image to a media such as paper or the like.
When an image is outputted to a laser beam printer as an example of the printer, intermediate output data suitable for the controller unit of the printer is formed by an apparatus such as a host computer or the like. The intermediate output data is generally formed by software called a printer driver. The intermediate output data is inputted to the controller unit of the printer via a network line such as parallel line, universal serial bus, Ethernet (registered trademark), or the like. The controller unit converts the intermediate output data into output image data suitable for the engine unit and outputs it as a video signal to the engine unit synchronously with an image transfer permission signal from the engine unit. In the engine unit, a video signal inputted by controlling and driving an electrophotographic process is outputted as an image onto a media such as paper or the like. Output timing of the image transfer permission signal from the engine unit is determined by a conveyance state of the paper, a state of the electrophotographic process, or the like.
The controller unit and the engine unit are connected by a communication path called a video interface. The video interface makes communication of a video signal for transferring the output image data, a control signal for controlling timing or the like of the video signal, a command signal for allowing the controller unit to instruct the engine unit, a status signal for allowing the engine unit to inform the controller unit of an engine state, or the like.
The conveyance state of the paper indicates a state of the paper in the engine, such as “during paper feed”, “during print”, “during paper ejection”, or the like. The state of the electrophotographic process indicates an idle state, an initialization state, a state showing “during a post-process”, or the like. The engine unit is not always in a printable state but, when the engine unit enters the printable state, it outputs the image transfer permission signal to the controller unit. The controller unit and the engine unit operate in intimate cooperation with each other by using the control signal, command signal, and status signal.
Also in a printer system such as an ink jet printer other than the laser beam printer, a data flow up to the print is similar to that mentioned above. The controller unit of the ink jet printer converts the intermediate output data from the host computer into the output image data suitable for the engine unit and outputs it as a raster signal synchronously with the engine unit. The engine unit controls and drives an ink jet process and forms the inputted raster signal as an image onto the media such as paper or the like.
In the development of the printer constructed by the controller unit and the engine unit as mentioned above, the following two points are particularly important.
1. Whether the printer operates at normal timing and a desired print speed has been accomplished or not.
2. Whether the image has been outputted normally or not.
In a developing step or an operation verifying step of the conventional printer, the intermediate output data is created by the host computer and transmitted to the controller unit, thereby actually making the engine unit operative and obtaining an output image (printed matter). By measuring an output time and directly observing the output image, the operation of the printer is evaluated and verified. Such a process for the creation of the intermediate output data, the measurement of the engine output and the output time, and the evaluation of the output image is repetitively executed.
According to the conventional method of obtaining the output image by actually making the printer operative, the printing operation cannot be executed unless the development has reached a stage where the development of both of the controller unit and the engine unit has progressed enough that both of them operate. It is difficult to reduce the development time and develop them in parallel. There are also problems in that the amount of printed matter which is subjected to the evaluation of an image and the measurement of the print time is very large, and a very long time and a large quantity of consumables such as toner, print paper, and the like are needed.
To solve the above problem, according to Japanese Patent Application Laid-open No. 04-055935, the printer emulating apparatus such that intermediate output data formed by a printer driver on a host computer is received and displayed as an image onto a display system such as a CRT or the like has been proposed. According to that printer emulating apparatus, the intermediate output data from the host computer can be verified without obtaining an output image by actually making the printer operative in the developing step of the printer.
In Japanese Patent Application Laid-open No. 2001-110529, the image processing apparatus such that a video signal which is outputted from a controller unit is received and visualized as an image onto a display system such as a CRT or the like has been proposed. According to such an image processing apparatus, the video signal which is outputted from the controller unit can be visualized and the output image can be verified without using the engine unit by a developing step of a printer.
By using the methods according to the above two proposals, the time which is needed to actually output the image and the consumables such as toner, print paper, and the like can be saved. The output image can be verified without using the engine unit. Distributed and parallel development of the engine unit and the controller unit can be realized.
However, the above two propositions have been made to confirm the intermediate output data and the output image data, and its function has been limited to a function of confirming the image at the printer development stage. Although importance is attached to “the normal timing and the desired print speed are accomplished” as mentioned above in the development of the printer, there is a problem such that the above two propositions are not effective with respect to the timing and the print speed.
The print speed of the printer is also influenced not only by ability of the engine unit for actually outputting the image but also by ability of forming the output image data of the controller unit. That is, even if the engine unit which operates at a high speed is used, the controller unit has to form the output image data at a high-enough speed and output the video signal. On the contrary, even if the controller unit formed the output image data at a high speed, unless the engine unit can operate in response to it, the whole printer cannot operate at a high speed. Since the speed of the whole printer is mutually influenced by the controller unit and the engine unit as mentioned above, it is hard to separate factors of restricting the print speed upon evaluation.
Further, since the speed of the printer is determined by intimate conditions of the engine unit and the controller unit as mentioned above, in the developing step of the controller unit, although detailed state change information of the engine unit upon execution of the print is necessary, since the controller unit is connected to the engine unit, it is difficult to obtain the state change information. Therefore, hitherto, an electrical waveform has been observed by a logic analyzer or the like, thereby presuming the state change of the engine, or a skilled engineer presumes the state change of the engine from an operation sound or the like of the engine by experience.